Triptolide represses oral cancer cell proliferation, invasion, migration, and angiogenesis in co-inoculation with U937 cells

Advanced oral cancer is a major public health concern because of a lack of effective prevention and treatment. Triptolide (TPL), a diterpenoid triepoxide derived from the Chinese herb Tripterygium wilfordii, has been demonstrated to possess strong anticancer properties. In this study, we investigated whether TPL exerts anticancer effects on the tumor microenvironment of head and neck squamous cell carcinoma (HNSCC). Human macrophage-like U937 cells were co-inoculated with oral cancer SAS cells in a noncontact transwell coculture system. Cytokine expression was detected using ELISA, and cell proliferation was detected using methylene blue. RNA levels were detected using qPCR. Protein levels were detected using Western blot analysis. In vivo experiments involved using xenografted NOD/SCID mice. Our results demonstrated that TPL inhibited the growth of SAS cells co-inoculated with U937 cells in vitro and in vivo. TPL inhibited the invasion, migration ability, and angiogenesis of SAS cells co-inoculated with U937 cells. Expression of cytokines IL-6, IL-8, and TNF-alpha was induced by co-inoculation, but TPL repressed their expression. TPL suppressed the expression of cytokines IL-6, IL-8, and TNF-alpha, as well as tumor growth, invasion, migration, and angiogenesis in the co-inoculation of human tongue cancer cells with macrophage-like U937 cells. TPL is a potential candidate among novel chemotherapeutic agents or adjuvants for modulating tumor-associated macrophages in a tumor microenvironment of HNSCC.